Niacin is a vitamin known as vitamin B3 or nicotinic acid. Its chemical name is pyridine-3-carboxylic acid. It is an essential vitamin for human health.
Niacin doses for therapeutic uses are about 1.5 to 6 g/day. However, at these needed doses side effects are common such as dermatological conditions that often are displayed as skin flushing, itching, dry skin and skin rashes including eczema exacerbation and Acanthuses nigricans. 
It has been thought that these symptoms are related to niacin's role as the rate limiting cofactor in the histidine decarboxylase enzyme, which converts 1-histidine into histamine. H1 and H2 receptor mediated histamine is metabolized via a sequence of mono- or di-amine oxidase and COMT into methyl histamine, which is then conjugated through the liver's CYP450 pathways. Persistent flushing and other symptoms may indicate deficiencies in one or more of the cofactors responsible for this enzymatic cascade.
Recently it has been thought that the flushing is primarily caused by prostaglandin (PGD2), with serotonin appearing to have a secondary role in this reaction.
The actual mechanism of this superficial vasodilator flush syndrome (SVFS) in humans is not completely understood as yet.
Besides the SVFS side effect from these doses of niacin, additional side effects have been reported, for example gastrointestinal complaints, such as dyspepsia (indigestion), nausea and liver toxicity (fulminant hepatic failure). Additional side effects of hyperglycemia, cardiac arrhythmias, and “birth defects in experimental animals” have also been reported. [Keith Parker; Laurence Brunton; Goodman, Louis Sanford; Lazo, John S.; Gilman, Alfred (2006). Goodman & Gilman's the pharmacological basis of therapeutics. New York: McGraw-Hill.]
The SVFS flush lasts for about 15 to 30 minutes and sometimes longer, and is sometimes accompanied by a prickly or itching sensation, in particular, in areas covered by clothing. This has made the use of niacin therapy difficult for many persons and they cease its use.
Various attempts have been made to mediate this SVFS flushing and other skin reactions. A few of these attempts are discussed below.
Some attempts for modulation of the SVFS effect have combined niacin with various other compounds, for example: a flavonoid composition (U.S. Pat. No. 7,923,043, U.S. Pat. No. 7,759,307); making derivatives of niacin such as niacinamid or, nicotinic acid esters (US Appln. 2004/0081672, published Apr. 29, 2004); taking aspirin or ibuprofen (US Appln. 2010/0292280, published Nov. 18, 2010); consumption with food or as a food supplement with other ingredients such as fish oil concentrate and lecithin (US Appln. 2003/0166614, published Sep. 4, 2003) and phosphatidyl choline, phosphatidyl inositol and/or phosphatidyl ethanolamine, lecithin, a mucopolysaccaride, and silicon dioxide, silicic acid and/or organic esters of silicic acid (U.S. Pat. No. 4,466,958), and using a niacin receptor partial agonist and a lipid altering amount of niacin (WO 2006/052569, published May 18, 2006).
Using niacin in a topical application has been tried by many formulations such as for cosmetic uses in U.S. Pat. No. 7,320,797, for increasing local blood flow with L-arginine and theophylline in US Appln. 2011/0028548, published Feb. 3, 2011, for treating dyshidrosis and skin diseases in U.S. Pat. No. 7,666,451.
Additionally, forming sustained release formulations to lower the SVFS flushing effect have been tried when therapeutic doses of niacin are needed (CA Patent 2,505,808, CA Patent 2,498,639, and CA Patent 2,494,743). A matrix formulation has been tried for sustained release as tablets (US Appln. 2008/0050429, published Feb. 28, 2008, US Appln. 2009/0069275, published Mar. 12, 2009). However, these sustained release formulations where doses are above 2 g/day have been associated with liver damage. Extremely high doses of niacin can also cause niacin maculopathy, which is a thickening of the macula and retina, which leads to blurred vision and blindness. This maculopathy is often reversible after niacin intake ceases.
Besides being a vitamin that is usually in many multivitamin tables, many foods contain this vitamin.
Other known uses of niacin are to increase high-density lipoprotein (HDL), or the “good” cholesterol, as the HDL will aid the body on getting rid of low-density lipoprotein (LDL), or the “bad” cholesterol, in the bloodstream. Thus niacin may help boost the body's HDL levels. It is important to avoid too low an HDL level as that alone can still increase the risk of heart disease even if the LDL level and other factors are normal. [Mayo Clinic.com]
For all these uses of niacin, the SVFS flushing and skin reaction have been a deterrent to its use.
Clearly, a safe, reliable, pleasant niacin formulation for use as a warming agent for a person's extremities when exposed to cold weather with minimal or none of these side effects and that can be used repeatedly over long periods of time is needed.